The number of UK homes valued at more than £1m has soared by nearly a third over the past 12 months. The huge increase in the number of property millionaires – with 1,500 new members joining the exclusive housing club every week – is revealed in a survey released on Friday by the property website Zoopla.

It also shows that the number of "million-pound streets" in Britain, where the average property value is more than £1m, has jumped by nearly a quarter over the past year. There are now 8,230 such streets – including nearly 3,000 in London and another 930 in the capital's wealthiest satellite towns, such as Kingston upon Thames, Richmond and Harpenden.

The number of homes valued at more than £1m has risen to 323,684 – a 32% increase in the past 12 months. The space taken up by a doormat in Kensington is now worth more than £3,500.

Separate figures from Lloyds TSB show that just four sales of million-pound homes took place in Wales during 2012, and nine in the north-east of England.

The huge concentration of million-pound houses in London and the south-east will fuel concern about what has been dubbed "the Manhattanisation of London" and the widening north-south divide.

In London's W8 district, which takes in much of Kensington and is home to many celebrities, the average house is now valued at £2.3m. At that price, a standard doormat of 0.24 sq metres (2.58 sq ft) would require a space worth just over £3,500.

The comparison with Britain's poorest streets is stark. In Stoke-on-Trent and Liverpool, the city councils have recently been inundated with applications after launching projects allowing people to buy derelict homes for just £1, while in Ebbw Vale and Tredegar in south Wales, property websites list page after page of homes for sale at under £50,000.

Henry Pryor, an independent property expert, said: "What the survey reminds us is that the property market is split in two – 'them and us' as well as north and south, and, far from being 'all in it together', the rich have prospered – and the rich in London have prospered the most."

He added: "Over 3m people are now on social housing waiting lists, and according to Shelter 14 years is required to save a first-time-buyer deposit. Meanwhile, house prices north of Luton are struggling to float on the choppy waters of the UK housing market.

"While the homes of the rich and famous are increasing by more than £100,000 a year, the majority of the nation's housing stock is stuck where it was a decade or more ago, and nearly 800,000 of those with a mortgage are in negative equity."

Overseas buyers are behind much of the boom in what upmarket estate agents are now referring to as a new mini city-state, PCL – prime central London. In 2012, of 7,000 new-build homes sold in prime central London, more than 5,000 went to overseas buyers, and the estate agency Knight Frank said buyers from just two countries, China and Singapore, bought 40% of them.

But buyers rarely occupy the properties, leaving parts of prime central London empty of residents and any remaining local shops bereft of customers popping out to buy a paper or pint of milk.

The main beneficiary has been the Treasury, which in March last year imposed a 7% stamp duty on home sales above £2m.

The new governor of the Bank of England, Mark Carney, who has his first day in office on Monday, may find that his £250,000 housing allowance fails to stretch far in London's superheated property market.

Rents in prime central London have soared alongside house prices, so that Carney's annual allowance is only enough to cover five weeks' rent for a five-bedroom flat in Knightsbridge currently being marketed by Savills.

The huge rise in property prices has left many young families despairing of ever affording a home. On Thursday, data company Experian said owner-occupation levels in some parts of the south-east were falling dramatically, citing Slough, Brent and Bournemouth as some of the "generation rent" hotspots where younger people were struggling to buy a property. In Slough, owner-occupation levels have fallen by 14% over the past decade.

The government's controversial Help to Buy scheme is aimed at helping first-time buyers to afford a property, but critics have warned that it will simply spark another price boom. This month Halifax said average house prices in Britain were rising at their fastest pace for two and a half years.

The number of British homes worth more than £1m has risen by almost a quarter since 2012, according to property website Zoopla - and as a result the number of streets where the average asking prices has broken seven figures is also up. It claims there are now 8,230 "millionnaire's rows" around the country. Here are the some of most expensive in London and beyond